So, let's start by taking a look at our play and pause functionality. We have a play button that changes to a pause button when the track is playing:.
We've already created an input node by passing our audio element into the API. For the most part, you don't need to create an output node, you can just connect your other nodes to BaseAudioContext. A good way to visualise these nodes is by drawing an audio graph so you can visualize it. This is what our current audio graph looks like:. We also need to take into account what to do when the track finishes playing. Our HTMLMediaElement fires an ended event once it's finished playing, so we can listen for that and run code accordingly:.
Let's delve into some basic modification nodes, to change the sound that we have. First of all, let's change the volume. This can be done using a GainNode , which represents how big our sound wave is. You can use the factory method on the context itself e. We'll use the factory method in our code:. Now we have to update our audio graph from before, so the input is connected to the gain, then the gain node is connected to the destination:.
The default value for gain is 1; this keeps the current volume the same. Gain can be set to a minimum of about Here we'll allow the boombox to move the gain up to 2 double the original volume and down to 0 this will effectively mute our sound. Let's give the user control to do this — we'll use a range input :. Note : Range inputs are a really handy input type for updating values on audio nodes. You can specify a range's values and use them directly with the audio node's parameters. So let's grab this input's value and update the gain value when the input node has its value changed by the user:.
Note : The values of node objects e. This is why we have to set GainNode. This enables them to be much more flexible, allowing for passing the parameter a specific set of values to change between over a set period of time, for example. Great, now the user can update the track's volume!
The gain node is the perfect node to use if you want to add mute functionality. There's a StereoPannerNode node, which changes the balance of the sound between the left and right speakers, if the user has stereo capabilities. Note: The StereoPannerNode is for simple cases in which you just want stereo panning from left to right.
Yes, in IE9. From OS [a]. ADTS [b]. From OS, in v Player object, after line The toMaster function is shorthand for connect Tone. At this point you may want to hear the sample. To do that, we need to add a button to the webpage, and program it to play the sample once pressed. We are going to use a NexusUI button in the body:.
You should now see a rounded button being rendered in the document. To program it to play our sample, we add a NexusUI listener, which looks like this:.
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You can set NexusUI to not do that, and instead have these variables only in nx. Same as in jQuery, we can put these. Here we are just assigning a function to whatever is done to the button. To play the sample instead of logging messages when we press the button, we should run the start function of our sampler. Also notice that the listener goes inside an onload callback.
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Just as you would do with DOM elements in jQuery. The event is triggered on mouse down and on release. If you want it to be triggered only on press, you have to evaluate whether event.
Web Audio API and Audio Visualization
With this, you should have a button that plays the sample on each press. If you set sampler. Otherwise, you have to wait until the sample finishes to retrigger it. The first argument is the delay time, which can be written in musical notation as shown here. The second is the wet level, which means the mixture between the original sound and the sound that has an effect on it. The next step is to unplug our sampler from master and plug it instead to the delay. Tweak the line where sampler is connected to master:.
Your First Steps with the Web Audio API
The parameters that you can tweak on each event can be found in Tone. For delay, it is here. Now you are ready to try the example and tweak the delay parameters with the NexusUI dials. This process can be easily done with each NexusUI element, not limited only to effects. For instance, also try adding another dial, and adding its listener as follows:. You can find these files at github.
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